1. Field of the Invention
The present invention relates to the field of laser device fabrication and, more particularly to a method and apparatus for holding laser wafers during a semiconductor fabrication process to minimize breakage of the wafers.
2. Description of the Related Art
Semiconductor laser devices are used in a wide variety of today's applications. These applications include, but are not limited to, optical telecommunications, stereo equipment, optical storage and printing devices. Examples of the laser devices used in these applications are fiber optic transmitters, compact disc (CD) players, CD-ROM drives and laser printers.
Laser devices utilize laser diodes to generate light signals or waves. Laser diodes are manufactured from semiconductor substrates or wafers. Typically, the wafer used in the fabrication of laser diodes is a gallium arsenide (GaAs) wafer, although wafers with other chemical compositions are also used ("laser wafer" will be used herein to describe a semiconductor wafer from which a laser diode is fabricated).
During the fabrication of a laser diode, the laser wafer undergoes a thinning process. This process, also known in the art as lapping, takes a relatively thick laser wafer and reduces it to a desired thickness. Currently, laser wafers are reduced to a thickness of approximately four mils (i.e., four-one thousandth of an inch).
To perform the thinning process, the laser wafer is mounted onto a wafer support. The wafer support is typically a sapphire disk, but it can also be quartz or a metal plate. Wax is used as an adhesive to ensure that the laser wafer adheres to and remains mounted on the wafer support. Once mounted, the laser wafer and the wafer support are inserted into a thinning or lapping apparatus where the laser wafer is mechanically or chemically reduced to the desired thickness. Once the laser wafer is thinned, the laser wafer, which is still affixed to the support, is removed from the apparatus.
Upon completion of the process, the laser wafer is removed from the wafer support. Typically, tweezers or a stick-like object is used to remove the laser wafer from the wafer support. Since the laser wafer is very thin, e.g., approximately four mils, there is a high incidence of breakage during this step. Broken lasers wafers require additional processing steps which adds cost to the manufacturing process. Accordingly, there is a need and desire for a method and apparatus for holding laser wafers during the thinning process that minimizes breakage of the laser wafers upon removal.
In addition, since the current methods utilize wax to adhere the laser wafer to the wafer support, the laser wafer must undergo a clean up step to remove wax build-up. This is time consuming, adds cost to the manufacturing process and is not always effective. Often times, even after the clean-up step, a wax residue remains on the laser wafer making them unsuitable for use in a laser diode. Accordingly, there is a need and desire for a method and apparatus for holding laser wafers during the thinning process that does not require a clean up step upon completion of the process.